<!--
 * @Descripttion: 
 * @Author: voanit
 * @Date: 2022-06-26 14:37:29
 * @LastEditors: voanit
 * @LastEditTime: 2022-06-26 14:45:39
-->
<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <script>
    const sum = (n) => {
      if (n === 1) return 1
      return sum(n - 1) + n  //  100 +99+98+97+96....1
    }
    console.log(sum(100));
  </script>
</body>

</html>